1) Field of the Invention
This invention relates in general to an assembly for bolting a caster to the framework base of platform trucks and wheeled rack units, and more particularly to such an assembly having sleeves each having a mouth to receive therein ends of a horizontally spaced pair of parallel tubular crossbeams, to form a rectangular framework's one side, and another tubular crossbeam extended perpendicularly with the crossbeam pair, to form the framework's other side.
2) Description of the Prior Art
There have been developed a variety of caster mounting bases for platform trucks, works trolleys and other wheeled load carriers, in which casters are mounted for wheeling and which also serve as corner joints. A typical mounting base, as disclosed in Japanese laid-open patent application 4-79771, has a horizontally spaced pair of parallelly extending sleeves, each having a mouth to receive therein ends of a pair of crossbeams, and another horizontal sleeve extended perpendicularly with the first sleeve pair and having another mouth into which an end of a third crossbeam is inserted. With this arrangement, four such mounting bases assemble crossbeams into a rectangular platform framework for wheeled load carriers.
However, the prior-art caster mounting bases for wheeled load carriers have proved to pose at least one major drawback, because of their possible failure to find a matched caster in terms of bolt pitch. Manufactures of platform trucks normally purchase casters which are assembled onto their trucks at the factories. Their concern is, however, that the bolt pitch of casters bought or ordered from outside producers may not fit that of bolt holes bored in their mounting bases.
One solution, if this happened, is to go and seek a matched caster in the market, which is time consuming. Another solution is to have a mounting base bored to have a multiple number of bolt holes in advance, in the hope that the selected combination of holes can find a matched caster.
The present invention has been proposed to eliminate the above-mentioned difficulty of conventional bold mounting bases.